Trypanosoma cruzi: inhibition of parasite growth and respiration by oxazolo(thiazolo)pyridine derivatives and its relationship to redox potential and lipophilicity

Chagas' disease constitutes a therapeutic challenge because presently available drugs have wide toxicity to the host and are generally ineffective in the chronic stages of the disease. A series of oxazolo(thiazolo)pyridene derivatives were studied on Trypanosoma cruzi epimastigote growth and oxygen consumption and their electrochemical (redox) potentials and lipophilicity. The derivatives produced different degrees of parasite growth and respiration inhibition on CL Brener, LQ, and Tulahuen strains of T. cruzi epimastigotes. Respiratory chain inhibition appears to be a determinant of the trypanosomicidal activity of these compounds, since a significant correlation between respiration and culture growth inhibition was found. A similar correlation was found, within the different structural subfamilies, between toxic effects and the ability of the compounds to be oxidized in aqueous media. The inhibition of respiration and of parasite growth in culture increases with the lipophilicity of the substituents on the oxazolopyridine nucleus. No difference in the action of these derivatives was found among the different parasite strains. It is concluded that these compounds may have a potential usefulness in the treatment of Chagas' disease.

Late sequelae of pontine lesions by acute uncal herniation

The authors report the late macro- and microscopic aspects of the brainstem lesions found in two patients who survived an acute uncal herniation, respectively, 176 and 62 days. They also describe the evolution of the clinical picture characterized by the complete disappearance of initially present neurological signs but by a persistent comatose state.

Trypanosoma cruzi: H2 complex and genetic background influence on the humoral immune response against epimastigotes

Using A.SW, A.CA, B10.S and B10.M congenic mouse strains, we measured the IgG specific humoral immune responses against sonicated and live Trypanosoma cruzi epimastigotes. Genes located in the A background (A.SW and A.CA strains) mediate higher IgG responses against the parasite antigenic complexes than those located in the B background (strains B10.S and B10.M), regardless of the H2 haplotypes. Thus, non H2 genetic elements seem to be more important in determining differences in the total IgG immune response against T. cruzi. Whether a detectable H2 effect, in favor of the H2(s) haplotype, occurred in the A or B background, was contingent on the immunisation protocol used. Thus, the H2(s) haplotype mediates a higher IgG response in the A background, if immunised with live epimastigotes, and in the B background against sonicated epimastigotes. Most likely this represents a complex sequence of events, controlled by non-MHC genes, involving antigen handling and processing and depending on the physical form of antigen delivery.

Effects of 3-chloro-phenyl-1,4-dihydropyridine derivatives on Trypanosome cruzi epimastigotes

A series of 3-chloro-phenyl-1,4-dihydropyridine derivatives produced different degrees of inhibition of parasite growth and respiration on clone Brener, LQ and Tulahuen strains of Trypanosome cruzi epimastigotes. Respiratory chain inhibition appears to be a posible determinant of the trypanosomicidal activity of this compounds. No difference in the action of these derivatives was found among the different parasite strains. For comparative purposes, the inhibitory effects of felodipine and nicardipine are also reported. A good correlation between toxic effects and the easiness of oxidation of the dihydripyridine ring was found. The presence of a fused ring on the dihydropyridine moiety significantly diminished the inhibitory effects.

Stretching (?) of the spinal cord as a cause of paraplegia in a patient with Cushing's syndrome

Paraplegia with a total anesthesia level was found in a patient who had Cushing's syndrome. There was marked osteoporosis of the spine and a moderate wedge shaped compression fracture of the T4 vertebral body but no stenosis of the canal could be observed. On the grounds of the CT findings stretching of the spinal cord caused by the rapidly evolving kyphosis of the thoracic tract has been thought to be the responsible factor of the clinical deficits.

Efficacy of corticosteroid therapy on cerebral gummas: risks and implications

Complete resolution of a cerebral gumma can take place after massive corticosteroid treatment. Such a result in patients not known as syphilitic can be misleading and hamper the identification of the true nature of the lesion.

Effects of some beta-carboline alkaloids on intact Trypanosoma cruzi epimastigotes

Several beta-carboline (9H-pyrido-[3,4-b]-indole) alkaloids were evaluated for in vitro trypanosomicidal activity against Trypanosoma cruzi epimastigotes belonging to two different strains (Tulahuén and LQ) showing different sensitivity to nifurtimox. Important differences were observed in the susceptibility of the parasites to these natural substances, with the relatively nifurtimox-resistant LQ strain showing greater sensitivity to the beta-carbolines. Respiratory chain inhibition appears to be a possible determinant of the trypanosomicidal activity of these compounds.

Involvement of thiol metabolism in resistance to glucantime in Leishmania tropica

Clinical resistance to pentavalent antimonials, in the form of pentostam (sodium stibogluconate) or glucantime (N-methylglucamine antimoniate), has long been recognized as a problem in Leishmaniasis. However, the mechanisms of resistance are unclear. We selected in vitro a Leishmania tropica line resistant to 1.2 mg/mL of Sb(V) of glucantime (GLU-R10). The cell line has a stable phenotype for at least 6 months and a resistance index of 1400-fold. The resistant line has no cross-resistance to pentostam or to SbCl3 and SbCl5. The resistance to glucantime was reverted by buthionine sulfoximine (BSO) and chlorambucil (CLB); however, thiol analyses by HPLC of wild-type and GLU-R10 cell lines, in the presence or absence of the drug, showed no differences between these two cell lines. The resistant line had a DNA amplification shown as a circular extrachromosomal element (G-circle) of approximately 22 kb. However, the specific probes for gamma-glutamyl cysteine synthetase, ornithine decarboxylase and trypanothione reductase did not recognize the G-circle amplified in the GLU-R10. The G-circle did not arise from the H region and was not related with P-glycoprotein Pgp-MDR- or Pgp-MRP-like genes. Northern blot analysis of the G-circle showed that a single transcript of approximately 6 kb was overexpressed in the resistant line. Molecular characterization of the G-circle would lead to the determination of the gene(s) involved in resistance to glucantime in Leishmania.

Nitro aryl 1,4-dihydropyridine derivatives: effects on Trypanosoma cruzi

A series of nitro aryl 1,4-dihydropyridine derivatives produced inhibition of both cell growth and oxygen consumption on Tulahuen and LQ strains, and clone Dm 28c of epimastigotes of Trypanosoma cruzi. Nicardipine was found to be the most potent derivative in both growth cell (I50 = 70 microM) and oxygen uptake (I50 = 26 microM in intact parasites, I50 = 325 microM in situ mitochondria). A correlation between the inhibitory effects on the growth cell and the apparent first order kinetic for the uptake of the 1,4-dihypyridine derivatives by T. cruzi epimastigotes was found. Thus, nicardipine, the most potent derivative, exhibited the highest apparent rate constant, ku, (0.043 min-1). On the other hand, no susceptibility differences by strains and clone Dm 28c to the action of these drugs were found.

[Discitis in childhood: integrated neuroradiological imaging in diagnosis and follow-up study of one case]

Discitis is an inflammatory disease of the intervertebral disc which has usually a benign evolution in childhood. It often recognizes an infectious etiology. Still discussed however is the possibility of a primitive discal involvement (not secondary to a vertebral inflammation) or of a non infectious etiology and the subsequent more correct diagnostic-therapeutic procedures. We report a case of a girl with discitis diagnosed early and treated with antibiotics and orthopedic corset, whose follow-up shows a benign evolution. We underline the importance of modern neuroradiological imaging: in particular, MR plays a major role in the inflammatory diseases of the column, both in diagnosis and in follow-up. MR scans of the involved disc allow frequent controls without radiogenic risks and with a good resolution because of the multiplanarity typical of the method.

[Phyolaryngocele: a case report and review of literature]

A case of pyolaryngocele presented as a lateral cervical mass that produced acute dyspnea requiring tracheotomy. The diagnosis was by direct laryngoscopy, which revealed outflow of purulent material with pressure on the tumor, and was confirmed by CT. Broad-spectrum antibiotic treatment was given and the pyolaryngocele was excised by lateral extramucosal tyrotomy. The literature on laryngocele and pyolaryngocele was reviewed.

[Topographic diagnosis of hearing loss in patients with ischemic heart disease. Use of high-rate brain stem evoked response audiometry]

Hearing loss in patients with ischemic heart disease traditionally has been attributed to atheromatous cerebral vascular disease. In this study, the site of the auditory lesion was sought in patients with ischemic heart disease and perceptive hearing loss. Standard brainstem evoked response audiometry (BSER) with increased stimulation rate (ISR) were performed. Sixty-seven patients admitted for coronary artery disease were examined. Fifty-seven recordings were complete and evaluable. All the cases of hearing loss were endocochlear. In 4 patients. BSER and ISR detected subclinical retrocochlear lesions that were compatible with ischemic disease. The results suggest that selective early cochlear ischemia can occur in young persons with heart disease. The sensitivity of BSER with ISR for detecting ischemic brainstem lesions was confirmed.

[Surgical multiple level reconstruction of the upper airways for treatment of obstructive sleep apnea. Two clinical cases]

Techniques for surgical correction of the soft palate are used commonly to treat obstructive sleep apnea syndrome (OSAS), but a satisfactory cure cannot be ensured because such techniques usually involve localized correction of the upper airways (UA) whereas UA collapse during sleep involves the entire length. The development of correction techniques for the entire extension of the UA may help to solve this problem. We report the first two cases of multilevel UA surgical reconstruction in OSAS performed in Spain. The excellent results obtained favor routine use of this type of surgery once it has been validated in clinical practice.

Glutathione and trypanothione in several strains of Trypanosoma cruzi: effect of drugs

Glutathione (GSH), trypanothione (T(SH)2) and glutathionyl spermidine (GSH-SP) concentrations were determined in the Tulahuén and LQ strains and the DM 28c clone of Trypanosoma cruzi. The concentrations of GSH, T(SH)2 and GSH-SP, expressed as nmol of GSH per g of parasite fresh weight, were 60.1, 397.8 and 103.9, respectively, for the Tulahuén strain. For the DM 28c clone, the values were 113.9, 677.9 and 164.1, respectively, and for the LQ strain they were 199.1, 1100.5 and 55.3, respectively. When the parasites were treated with 10 microM nifurtimox or 50 microM benznidazole for 2 h, the concentrations of all three reduced thiols decreased strongly. The total amount of T(SH)2 decreased by more than 50%. Treatment of the parasites with 5 mM buthionine sulfoximine, an inhibitor of GSH synthesis, for 6 h diminished the concentrations of the reduced thiols by between 27% and 53% with respect to the controls. Cyclohexylamine, an inhibitor of spermidine synthesis, decreased the concentrations of T(SH)2 and GSH-SP but not that of GSH. It is possible to conclude from this study that trypanothione is the most important thiol involved in the detoxication of nifurtimox and benznidazole in T. cruzi and that electrophilic reduced metabolites of both drugs are most probably conjugated with GSH, T(SH)2 and GSH-SP, thus decreasing their concentrations. GSH biosynthesis is an important drug target.

Time-course of stepwise CPAP titration. Behavior of respiratory and neurological variables

Because successful medical treatment of obstructive sleep apnea/hypopnea syndrome (SAHS) depends on adequate CPAP treatment, we have analyzed in nine SAHS patients the behavior of respiratory and neurological parameters during a stepwise, polysomnography-controlled CPAP titration to achieve an optimal CPAP. Particularly, we have focused on which simple variable could predict the optimal CPAP pressure and could better define a distinctive optimal-suboptimal pattern. Main parameters analyzed through the CPAP titration procedure were respiratory events (apnea, hypopnea), the contour of inspiratory flow, the pleural pressure behavior, the thoraco-abdominal motion, oximetry, arousals, and sleep stage. During the CPAP titration we observed: (1) a rounded shape in the inspiratory flow contour was associated with the lowest esophageal pressure; (2) during stepwise increases in CPAP, almost all apnea events changed to hypopnea periods, followed by prolonged periods of limited inspiratory flow with still high esophageal pressure but without arousals (probably suboptimal CPAP); and (3) as CPAP reached suboptimal levels, sleep stage moved to deeper stages without arousals. We conclude that if during CPAP titration the end point is the disappearance of arousals, most patients with SAHS will still exhibit periods of high intrathoracic pressures with limited inspiratory flow. Alternatively, if the end point to be reached is the lowest esophageal pressure, higher CPAP levels will be needed. The contour of inspiratory flow appears as the simplest variable that best correlates with lowest esophageal pressure during CPAP titration.

Effects and mode of action of 1,4-naphthoquinones isolated from Calceolaria sessilis on tumoral cells and Trypanosoma parasites

The naphthoquinones 2-hydroxy-3-(1,1-dimethylallyl)-1,4-naphthoquinone (CS-1), (-)-2,3,3-trimethyl-2-3-dihydronaphtho[2,3-b]furan-4,9-quinone (CS-3), and 2-acetoxy-3-(1,1-dimethylallyl)-1,4-naphthoquinone (CS-5) isolated from Calceolaria sessilis were tested against Trypanosoma cruzi epimastigotes, the TA3 tumor cell line and the methotrexate-resistant subline TA3-MTX-R. Naphthoquinone CS-3 was the most active; the 50% culture growth inhibition (I50) on T. cruzi (Tulahuén and LQ strain and DM28c clone) was at concentrations ranging from 2.1 to 5.2 mumolar. Also CS-3 inhibited TA3 and TA3-MTX-R culture growth with an I50 of 2.1 and 3.8 mumolar, respectively. Naphthoquinone CS-3 inhibited the respiration of the tumor cells by interfering with the electron transport at some point between NADH and ubiquinone. The respiration of T. cruzi was not inhibited by naphthoquinone CS-3. Naphthoquinone CS-3 produced a temporary increase of oxygen consumption in T. cruzi and tumor cells, suggesting the generation and participation of free radicals.

Purification and preliminary sequencing of Tc-45, an immunodominant Trypanosoma cruzi antigen: absence of homology with cruzipain, cruzain, and a 46-kilodalton protein

In spite of being separated by more than 20 million years of evolution, the murine and human immune systems share extensive similarities. Thus, experimental results obtained with the murine model may have predictive value for human Chagas' disease. Challenge of the H-2 congenic mouse stains A.SW (H-2s) and A.CA (H-2f) with Trypanosoma cruzi yields different results. The A.CA animals die approximately 12 days postinfection, while A.SW mice survive indefinitely. A 45-kD protein (Tc45), an antigen differentially recognized by the A.SW strain, is present in cultured epimastigotes and blood trypomastigotes. We describe here its purification from epimastigotes. The presence of Tc45 was monitored and a single band was detected. Since the molecular weights of Tc45, cruzipain, cruzain, and a 46-kD parasite polypeptide are similar, it was important to determine if these molecules are related. A complete lack of homology was observed when the sequence of cruzain, cruzipain, and the 46-kD polypeptide were compared with the preliminary sequence of Tc45.

[Adaptable and portable cephalometric devices: a new method in obtaining cephalometrics]

Cephalometric radiographic explorations are widely recommended in the diagnosis of the obstructive sleep apnea syndrome (OSAS). In order to improve their diagnostic value, its practice in the upright and supine position has been proposed. A rigorous practice of cephalometric requires the employment of cephalometric devices in order to assure a correct positioning of the head and provide reliable X-ray pictures, comparable within reasonable accuracy over a period of time. The commercialized cephalostats are often expensive due to the structural conditions needed for their development and usually they not allow the simultaneous practice of upright and supine cephalometric. In this paper we describe a cephalometric adaptable device, developed by our research group, that may solve such problems.

[Carotid paraganglioma: a case report]

Carotid paraganglioma are tumors arising from chemoreceptor paraganglioma cells. These cells have proved to have an embryologic origin from the neural crests. Due to their low incidence these tumors are not an habitually found in daily practices. We present a case of carotid body paraganglioma diagnosed by clinical exploration, CT scan, magnetic resonance imaging and magnetic resonance angiography which was successfully treated by surgery. The diagnostic and therapeutic difficulties present in these tumors are discussed.

[Neurosensory hearing loss associated with ischemic heart disease. Features and prognostic values]

The aim of this study was to verify the supposed pathological hearing loss in those patients with ischemic heart disease, as well as to determine its features and possible clinical usefulness. Two groups were made: group A (n = 65), patients admitted for acute episode of ischemic heart disease, group B (n = 60), patients without cardiac or auditive disorders. Auditive assessment included standard PTA and Bera. Cardiologic evaluation was made through cardiac catheterism with coronariography. Results confirm the existence of a clinical association between "perceptive hearing loss" and "ischemic heart disease", independently of the age, with a characteristic pattern of hearing loss, and also show the existence of a high risk subgroup within the population with coronary risk.

Trypanocidal effect of boldine and related alkaloids upon several strains of Trypanosoma cruzi

The alkaloids boldine, glaucine, predicentrine, apomorphine, coclaurine, norarmepavine and codeine were tested against the epimastigotes of the Tulahuén and LQ strains and the DM 28c clone of Trypanosoma cruzi. The micromolar concentration to inhibit 50% of the culture growth (Tulahuén strain) for apomorphine, glaucine, predicentrine, boldine, norarmepavine, coclaurine and codeine were 29, 90, 85, 110, 310, 580 and > 1000 respectively. Similar values were obtained with the LQ strain and the DM 28c clone. The most active compounds in inhibiting culture growth also inhibited cell respiration, suggesting that these drugs may act by blocking mitochondrial electron transport. The trypanocidal effects of these alkaloids appear to be correlated with their antioxidative activities.

Effects of hydroquinones on intact Trypanosoma cruzi epimastigotes

1. Hydroquinones inhibited the culture growth of Trypanosoma cruzi epimastigotes at concentrations lower than 1 mM. 2. Hydroquinones inhibited the oxygen consumption on the intact Trypanosoma cruzi cells. I50 values for hydroquinone, terbutylhydroquinone and 2,5-di-t-butylhydroquinone were 24.87 mM, 0.88 mM and 0.26 mM, respectively. t-Butylhydroquinone and 2,5-di-t-butylhydroquinone had a Michaelian type kinetic inhibition; hydroquinone also showed a Michaelian type kinetic inhibition at low concentrations but at higher concentrations it showed a positive cooperativity. 3. These hydroquinones changed the NAD(P) redox-state to a more reduced state and that of cytochrome b to a more oxidized state. The magnitude of the redox-state change was dependent of the hydrophobicity of the derivates. 4. These results suggest that the growth and oxygen uptake inhibition by the hydroquinones is due to a blockage of the mitochondrial electron transport chain before cytochrome b.